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Thread: Energy Efficient House Design

  1. #31
    Join Date
    Sep 2006
    Location
    Deep South
    Posts
    3,970
    I don't think there is a single best solution for everywhere. One has to calculate the cost/benefit ratio for the weather and political climate. I pay 1/3 to 1/4 the price of electricity as California. It is the same as solar power. A practical system for CA would never come close to breaking even where I live.

  2. #32
    Join Date
    Sep 2006
    Location
    Las Cruces, NM
    Posts
    2,037
    Quote Originally Posted by Jim Becker View Post
    Matt, I don't disagree, but with closed cell spray foam, you can balance the lower material cost of 2x4 walls with the higher initial cost of the insulation and end up better than you would have with 2x6 and conventional insulation...
    Ignoring energy efficiency (!), what the best insulation from the point of view of tearing into a wall to fix or modify wiring and plumbing? My only experience along those lines is tearing into walls that have ancient paper insulation that looks nasty and disintegrates when disturbed. I imagine foam to be something harder to get out of the way yet leaving "cleaner" debris.

    There are YouTube videos criticising Great Stuff "Fireblock" foam as being easily ignited. Is the type of foam used to insulate whole houses less or more of a fire hazard than other types of insulations?

  3. #33
    Join Date
    Mar 2003
    Location
    SE PA - Central Bucks County
    Posts
    65,685
    Stephen, I know that the closed cell foam used in our addition has a fire retardant in it and it's even ok that it's exposed in the attic area which is conditioned space within the envelop. But it's absolutely true that doing retroactive wiring and other things is pretty darn hard with spray foam in the wall, especially if the bays are filled. You can't just "fish" something. For anything beyond just a couple of feet, the best way would be to cut a channel in the drywall to gain access to the full extent of the wiring to be added, cut out a channel in the wall for the wire, do the installation and replace the strips of drywall with the required tape/mud, etc. Alternatively, pre-installing conduit can be helpful for some "anticipated" changes/additions. Unlike cellulose with a binder blown into walls and smoothed before covering (or other similar materials) closed cell foam is very rigid. Open cell foam is less so and closer to the cellulose with binder filler, but still not fun to retrofit through without fully exposing it. Honestly, fishing through fiberglas bats under drywall isn't a piece of cake either!
    --

    The most expensive tool is the one you buy "cheaply" and often...

  4. #34
    Join Date
    Apr 2017
    Location
    Michigan
    Posts
    2,758
    So again, spend your money and effort at the top of the list. 2x4 or 2x6, fiberglass or foam, not going to make a measurable difference. Infiltration is number one.

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